It would be hard not to cheer the results of Iran's weekend presidential election, if only for the moment.

The surprise winner, cleric Hasan Rowhani, is by all accounts the least extreme candidate voters could have picked, and "least extreme" is about as good as it gets in Iranian politics. More moderate contenders were barred from the ballot.

Better yet, Rowhani's resounding victory over six hard-line opponents was a stinging rebuke for the country's supreme leader, Ayatollah Ali Khamenei. The rigid and isolated Khamenei had confidently urged a massive turnout as a symbol of defiance in the face of economic sanctions aimed at blunting Iran's nuclear weapons program.

He got the turnout, not the hoped-for message.

Iran's restive urban middle class, which saw Khamenei steal an election four years ago, has chafed under political repression ever since. No surprise, then, that people saw hope in Rowhani's promises of freedom and engagement.

In the long view at least, it is a promising sign that Iranians might eventually shuck the theocracy that has ruled their lives since 1979. The population is young, partially Westernized and suffering though inflation and shortages caused by the sanctions. Their discontent seems sure to grow.

But to assume that this new "least extreme" president will magically ease the rapidly approaching crisis over Iran's nuclear program would border on fanciful.

In his first news conference Monday, Rowhani showed no sign of moderation. He reiterated the policies of outgoing president Mahmoud Ahmadinejad and rejected any potential for slowing Iran's enrichment of uranium, the critical issue in its nuclear program. Despite the flurry of optimism that greeted his election, there's reason to believe those positions are more than posturing.

The new president's reputation for moderation is based largely on his actions as Iran's nuclear negotiator from 2003 to 2005, when Iran voluntarily suspended uranium enrichment. He has since defended the suspension as a means of advancing the nuclear program by reducing external pressure and buying time to ease internal tensions.

The program has progressed much further since then and now is widely believed to be within months of crossing the line that both the Israeli and American governments have said would prompt an attack on the nuclear facilities, and with it high risk for a full-on war.

That moment will bring vexing choices with fateful outcomes.

To the extent that there's promise in Rowhani's election, it is that his instinct for pragmatism could lead him to press Khamenei to stop the program short of the West's red line, leaving Iran capable of nuclearizing but not actually doing it.

The U.S. and its allies should offer Rowhani relief from sanctions in exchange for a credible commitment to that goal. But they will have to proceed with a skeptical eye. Rowhani is not a moderate as much as he is a skilled tactician likely to continue Iran's stalling tactics.